1. Field of the Invention
The present invention relates to an optical power monitoring apparatus, an optical power monitoring method, and a light receiving device.
2. Related Background of the Invention
An apparatus for monitoring the power of an optical signal or the like under transmission is used in optical transmission systems and others. An optical power monitoring apparatus disclosed in PCT International Publication WO97/06458 has a first optical waveguide, a second optical waveguide, an optical filter, and a light receiver. The first optical waveguide and the second optical waveguide are arranged so that their respective end faces face each other. The optical filter is disposed in an inclined state between the respective end faces of the first optical waveguide and the second optical waveguide. The light receiver is provided beside the optical waveguides.
In this optical power monitoring apparatus, light propagates through the first optical waveguide and emerges from the end face thereof to the outside, part of the light is reflected by the optical filter, and the rest passes through the optical filter. The light passing through the optical filter is incident to the end face of the second optical waveguide and then propagates through the second optical waveguide. On the other hand, the light reflected by the optical filter is received by the light receiver. Then the light receiver outputs an electric signal at a value according to the power of the light received thereby, and the power of the light propagating from the first optical waveguide to the second optical waveguide is monitored based on this electric signal.